Method of treating paper



F.- DE WITT MET/fion oF ,HEATING PAPER Fil'ed Jan. 7, 1938 RN EYSPatented Dee. 19, 1939 UNITED STATES PATENT oFF-Ice 2,183,111 mamon' ormesme Paras Francis. ne wm,- New York, N. Y., signor u .Bei'velCorpratlon, New York, N. Y., a corporation of Delaware ApplicationJanuary "l, 1'938, Serial No. 183,756

-4Claims.

-tile fabrics. y l

Paper has been andy is used for many types of manufactures, such as, forexample, disposable tissues, hand towels, decorative articles, tablecovers and the like. The papers used forl these articles vary, but theyhave certain characteristics which render them unsuitable for 'moregeneral usage. Papers which have aA soft texture are low in mechanicalstrength and therefore are not durable either dry vor wet. Papers havinghigh mechanical strength are hard or harsh in texture and lackpliability or the feel that characterizes textile fabrics.

Recently papers have been develope'd, such as those disclosed in theSchur Patent No. 2,035,204. patented March 24, 1936. having so-calledwet strengt These papers are substantially as strong and tear resistantwhen wet as whenv dry; However, they lack pliabillty or drapability andas a consequence are not satisfactory substitutes for cloth. Whencrushed or crumpled, creases of wrinkles are formed in wet strengtpapers which cannot be readily removed and therefore their utility isrestricted tothe disposable types of articles of manufacture. It hasbeen suggested previously that man l types of papers can. be softenedand rendered pliable by impregnation with glycerine or other polyhydricalcohols or derivatives of the` same.

These softening agents, however, are water sol-` uble and upon wettingmay be dissolved and removed, allowing thepaper to become hard and harshupon drying. The softening agents may also evaporate or be drawn fromthe paper if it is brought in contact with other absorbent materials.

The'principal object of this invention, therefore, is to provide amethod of treating paper to render it pliable and soft in texture andcapable ,of being moistened without losing these characeither wet ordry, and capable of being cut' and sewed in the manner oi' textilefabrics.

Other objects of the invention which will become apparent as typicalembodiments of the invention, are vdescribed hereinafter.

In my co-p'ending application, Serial No. 183,800 flied the 7th day ofJanuary, 1938,- I have disclosed paper articles which are made inaccordance with this invention. The paper articles obtained bypracticing my novel process are characterized by good mechanicalstrength, pliability, flexibility and other characteristics, such asnormally associated with textile fabrics of the smooth nish type. Inaddition to these characteristics, these novel papers are impervious todust. 'Ihese papers may be used, for example, in the manufacture ofhospital supplies, home supplies and ofiice supplies of which doctorsaprons, dentists bibs, sheets, pillow cases, table linens, articles ofapparel theatre decorations and costumes.

In my co-pending application, Serial No. 183,801 iiled the 7th day ofJanuary, 1938, I have dislclosed a sizing or impregnating compositionwhich is used in practicing the process embodying this invention.l Thesizing or impregnatng compoav sition is characterized by the presence ofa paper softening agent, such as for example, polyhydroxy alcohols andderivatives ofthe same, such as glycerine, glycol, diethylene glycolandA the ethers and estersof polyhydroxy alcohols. 'I'hese papersoftening agents are water soluble, are stable and have boiling pointssuiciently in excess ofor greater than water, .whereby they will beretainedin the paper even if it is heated as high or above the boilingpoint of water.

In addition to the paper softening agent, the sizing and coatingcomposition contains water insoluble pulverulent ,mineral Ifiller whichfixes' or anchors the paper softening agent in the paper by retaining itmore tenaciously than is the tendency of the paper softening agent ytogo into solution in water. The preferred type of mineral filler materialmay be one or more of the group of water insoluble calcium, magnesium oraluminum salts, of which the silicates, fiuorides,sul fates, salcylatesof calcium and magnesium and the aluminum silicates, such as kaolin and-pumice,'are typical. In finely divided form these fillers may bedistributedthroughout the papers in accordance with the processembodying the in,

vention and adhere tenaciously to the bers of the. paper and at the sametime adsorb the paper softening agent so that it is retained even whenthe paper is wetted. I

In practice, the sizing or impregnatinur composition is applied inaccordance with this invenafter removing the moisture from the paper bydrying on drying drums or by festooning the -paper over suitablesupports in a drying room.

The sizing bath consists of an aqueous solution of the paper softeningagent, the water content of which may vary in accordance with the typeof paper being treated 'and the degree of pliability or softness whichit is desired to obtain.

IFor a better understanding of the present invention, reference may behad to the single figureof the drawing which discloses diagrammaticallyand in perspective a typical form of device for applying the sizingcomposition to the paper.

As illustrated in the drawing, the device may consist of a tank I havinga tapered bottom' I2,

desired type which forces the liquid through a conduit I8 to amixingtank 20 where the sizing and impregnating bathmay be strengthenedor replenished. A suitable outlet conduit 22 allows the sizingcomposition to be returned from the mixing tank 20 to the tank I0 and isprovided with a valve 24 for regulating the amount of sizing compositionto be delivered to the tank I0.

'Ihe tank Ill-is provided with a roller 26 under which a sheet of paper28 is passed in order to completely submerge the sheet in the sizingcomposition. The sheet of paper 28 may be delivered from a large roll 30and looped around a pair of idling or driven rollers 32 for smoothingand removing bulges or wrinkles from the sheet. The sheet 28v passesthrough the sizing composition under the roll 26 and over and around apair of driven drying rolls 3l and 36, which remove the excess waterfrom the sheet. The dried sheet is then rewou'nd on a roll 38 at theback end of the machine. Since the ller material is a nely divided waterinsoluble mass it has a tendency to settle outA and therefore anagitator 40 driven in any suitable way, such as, for example,

.by electric motor 42, is provided for maintaining the filler insuspension.

Typical examples of the sizing and impregnating bath may be as follows:

Example I Glycerine uid ounces-- 28 70% denatured alcohol -do 4 28 Waterdo '72 Magnesium silicate ounces-- 14 These proportions may be varied asby varying the water content to vary the concentration of glycerine andmagnesium silicate in the sizing composition whenlit is-desired to.apply a greate` or lesser amount of'these ingredients to the paperForexample, a heavy, thick-bodied paper preferably will be treated witha greater concentration of glycerine and magnesium silicate in order tos'often it to a predetermined point than would be required to treata'lighter paper or one naturally more soft to render it of the samedegree of pliability and softness. 'Ihe alcohol has the effect ofcausing the paperto dry more rapidly after treatment, but is not anessential ingredient of the sizing bath. The filler material, magnesiumsilicate, may be replaced by magnesium fluoride or oxide or by calciumvcarbonate, salicylate, or sulfate, or any water insoluble aluminumcompound, such as the silicates of which kaolin, fullers earth andpumice are typical examples. If desired, mixtures of these compounds maybe used with equal facility.

Another example which in actual practice has been foundentirelysatisfactory is as follows:

Example II Glycerine uid ounces-; 28

Water do. 80

Magnesium silicate', or other water insoluble mineral ller of the typeset forth in Example L ounces-- 16 The proportions of paper softeningagent and filler material may be varied within narrow limits. An excessof glycerine over the adsorptive power of the filler will cause a changein the texture of the paper upon wetting. Likewise, an excessive amountof filler will tend to provide a harder and smoother surface on thepaper which may or may not be desirable under certain circumstances.

'Ihe process consists generally of treating the papers, such as, forexample wet strengt papers, by passingthe paper through or dipping itinto a bath of the sizing composition above set forth, and thereafterdrying the paper to dry off the moisture.

The resulting product is a flexible, pliable paper which has a soft,moist texture, and a durability which is at least equal to thedurability of the same untreated paper. If the original untreated stockis Wet strength stock, the articles made therefrom may be moistened,stretched and smoothed without tearing and without any decrease ofstrength or pliability. Papers of this type are quite similar in textureto the smooth finish textile fabrics and. therefore can be cut and sewedby the same types of machines used in cutting and sewing the textilefabrics.

In addition, because of the pliability, drapability of the paper, it maybe crumpled or crushed and thereafter smoothed without leaving any vis,ible Wrinklesor creases therein. This characteristic is of materialimportance in the production of such articles as b'ed linens and tablelinens, as well as other hospital and home supplies. The hospitalsupplies may, if desired, be sterilized because there are no ingredientstherein which would be removed or deleteriously affected by heating orby the presence of suitable antiseptic agents, and they, therefore, havegreat utility in hospital usage.

It will be seen from the preceding description that through my method, Ihave been able to vproduce paper and paper manufactures which have manynovel characteristics not found in other papers. It should beunderstood, of course, that the examples given are illustrative and aretherefore not to be consideredas limiting the scope of the followingclaims. I

I claim:

1. The process of treating paper to render it soft an`d flexiblecomprising the steps of applying to the paper a solution containing, inthe following proportions, about '72 to 80 fluid ounces of water andabout 28 fluid ounces of a paper softening agent of the class ofcompounds consisting of water soluble, stable polyhydroxy alcohols andethers and esters of polyhydroxy alcohols having boiling points higherthan water and containing about 14 to 16 ounces avoirdupois of finelydivided water-insoluble mineral filler capable of adsorbing the papersoftening agent, and thereafter removing the water from the paper.

2. The process of treating paper to render it soft and pliable.comprising the steps oi' apply ing to a sheet of wet strengt paperhaving substantially l the same mechanical strength whether wet or dry asolution containing in the following proportions about 'I2 to 80 fluidounces of water,v 28 fluid ounces of a paper softening agent and about'14 to 16 ounces avoirdupois of a water-insoluble mineral iller, andthereafter drying the paper to produce a paper having high u about thefollowing proportions 28 fluid ounces of glycerine, 'I2-80 fluidouncesof water and 14-16 ounces avoirdupois of a finely-dividedwater-insoluble mineral iller capable of adsorbing the glycerine and (2)removing the water from the paper.

4. The process of treating paper to render it soft and lpliablecomprising applying an aqueous solution of a paper softening agent andcontaining a nely-divided water-insoluble mineral iiller and drying saidpaper, said solution containing inl the following proportions about 28fluid ounces of paper soitening agent, 'I2-80 iiuid ounces of water and14-16 ounces avoirdupois of filler. FRANCIS DE WITT. v

